Early adolescence represents a key transition period in development yet little is known, particularly for children in rural poverty, about the ways in which trajectories established in early childhood support or constrain the development of self-regulation with implications for key outcomes. Accordingly, we propose to continue to follow a population-based predominantly low-income longitudinal sample known as the Family Life Project (N=1292 oversampled for African American ethnicity and poverty). Extensive child, family, home, and school data were collected through two rounds of funding as an NICHD program project with 11% attrition. Data collection beginning at child age 2mos through age 8yrs occurred in 10 home visits, 5 childcare visits, and 8 school visits. In this follow-up, we continue to focus on child self-regulation and stress response physiology, as well as family, peer, school, and neighborhood contexts measured in the first two phases. Data will be collected in 1 home visit (7th grade) and 2 school visits (6th & 8th grades.) We will test specific hypotheses about the influence of the timing and chronicity of poverty-related adversity in families on the development of stress response physiology and self-regulation from early childhood through early adolescence. Most importantly, we will test hypotheses about the ways in which peer, school, and neighborhood contexts increase or decrease risk for key outcomes, including mental health, substance use, and school achievement. Primary innovation in this phase concerns our ability to test key questions about the malleability of self-regulation development and the role of emerging sensitivity to reward and delay in risk taking behavior in early adolescence. We hypothesize that alterations to the stress response and accompanying self-regulation difficulties will be most severe and most likely to lead to poor outcomes for children facing sustained high levels of poverty-related adversity; however, we also hypothesize that this influence will be moderated by the quality of peer relations, as well as school, and community characteristics. Specifically, for children facing sustained adversity, higher quality peer relatios (taking into account potential bidirectional relations between self-regulation and peer quality, including social isolation and affiliation with deviant peers), higher levels of school quality, an higher levels of neighborhood quality will each be associated with improvements in stress responsivity and in self- regulation abilities, and thereby higher achievement, reduced substance use, and better mental health. To our knowledge this is the first study of its kind to test complex longitudinal relations among adversity, stress response physiology, self-regulation, and key outcomes across multiple geographically and economically defined social contexts in a population-based sample. By testing the malleability of development using a psychobiological model, the proposed research will have clear implications for prevention efforts and efforts to promote positive youth development.